The present invention relates to a novel and useful fluid mass flow metering device.
Mass flow meters are often used in conjunction with other mechanical entities such as micro-atomizers, oxygen delivery systems, valve controlled devices, pressure regulators, compressors, and pumps.
In the past, mass flow meters have taken various forms. For example, the coriolis system requires high pressures to operate and is limited by the density of the fluids being measured. Coriolis measurement devices are also very expensive to manufacture since they require adjunct devices and computers to determine density. Also, coriolis flow meters do not measure low-density gases in a reliable manner and require high pressure to operate.
Non-intrusive magnetic flow meters, although not interfering with the flow being measured, require an enormous amount of electronic equipment to measure the magnetic field change of a fluid, based on magnetic flux. Also, a magnetic medium, such as powdered metal, must be placed in the fluid to amplify sensitivity of this system.
Doppler sonic effect flow meters, again, are non-obtrusive, however, and associated density determining mechanisms are required to measure flow in a conduit are extremely complicated and expensive.
Thermal mass meters employ a bypass capillary heating system relative to the main flow conduit. In this regard, the capillary mechanism must be maintained in an extremely clean condition. Also, determination of the exact type and density of the fluid being measured is a prerequisite to accurate measurements. In addition, thermal mass meters are very expensive to manufacture and maintain.
In the past, objects of a defined shape have been placed in conduits to effect the fluid flow. For example, U.S. Pat. 4,812,049 describes a fluid dispersing means in which a cone like member is placed in a conduit or pipe to disperse fluid component by creating turbulent flow downstream from the element.
U.S. Pat. Nos. 5,363,699 and 5,814,738 describe fluid flow meters in which flow measurements are taken along a conduit in conjunction with one or more displacement members.
U.S. Pat. No. 4,638,672 teaches a fluid flow meter where a fluid flow member of double conical configuration is placed in the fluid to determine the velocity profile. Fluid is passed through an auxiliary flow tube in order to affect measurement by a flow meter.
A fluid mass flow metering device which produces accurate measurements over a wide range of fluid flow rates would be a notable advance in the field of measuring instruments.